An in-depth general explanation of PVP IV’s, scroll to last paragraph for specifics.
Just a disclaimer: better PVP IV’s don’t play as big of a role as people think they do. They can be the difference between rank 9 and rank 10, or between 3000 and 3300 elo, but won’t stop you from getting to rank 6-8. Climbing early elo depends purely on your skill in teambuilding and inside the battle. That being said, better PVP iv’s will perform slightly better in clutch 1-2 fast move scenarios, which I’m sure we have all been in.
It has to do with how stats scale in pokemon go. At every level, each pokemon has a possible CP range based on it’s IV percentage. Let me give you an example –
A 100% level 20 Toxicroak will have a CP of 1421. A 0/0/0 level 20 Toxicroak will have a CP of 1212, a huge difference. As you can see, there is a big difference. With each “15” IV, it will gain about 70 CP, which accounts to about 2-3 power-ups.
A level 23 Toxicroak with 0/15/0 IV’s will have the following stats:
Attack: 135.18, Defense: 94.82, HP: 124.
A level 23 Toxicroak with 15/0/0 IV’s will have the following stats:
A: 144.79 D: 85.21 HP: 124
Now, at the core of this is the following concepts: Natural bulk is almost always more valuable than glassiness in PVP (yes, Haunter exists), and offensive strength almost always comes from more powerful moves. rather than glassy stats Thus, you see pokemon like Altaria and Registeel dominate the Great League with fantastic bulk and oppressive movesets (Dragon Breath, Lock on in combination with absurdly high-damaging charge moves). Essentially, the most important thing is that these Pokemon survive for long enough to get those moves out, otherwise they will simply be able to be farmed down and will become a risky investment in terms of shields.
Back my example of level 23 Toxicroaks (which both will be around ~1480 CP). When finding the ideal IV combination for Great League, you are looking to find ways to maximize a pokemon’s bulk, often at the cost of their immediate attack stat. Having a 0/15/15 IV (or following the framework of low attack stat and high def/hp) will allow for that, simply because of the way the mathematics work. It will have lower CP, and will be able to be powered up 2 or 3 times more. With each power up/increase in level, the stats will grow even more, which will allow your pokemon to reach higher defense/hp stats than it would as a 100% IV of lower level, and you will be able to reach a higher stat product under the CP cap (whether it be 1500 or 2500). A 100% IV will have a little bit higher attack, but also a little bit lower bulk and overall survivability because it will have the same defensive IV’s but will be lower level. Now, if you have a 0/15/15 and power it up 3 extra times – yes, your pokemon MAY do less damage per fast and charged move by a little bit (it also might not, depending on how much it’s Attack stat increases with level), but it will get several more fast moves off (and maybe even an extra charged move) because it will have substantially higher bulk.
PVP Pokemon have a unique “100% IV” that refers to maximum stat product, prioritizing bulk. A great resource for PVP IV rankings is gostadium.club. However, if your pokemon maxes out below the CP cap (medicham, sableye max below 1500, Registeel below 2500 etc) then you do want the 100% IV’s. Also keep in mind that 0/15/15 is not always the best IV setup, and sometimes will have lower stat products (gostadium.club) than slightly different IV’s, and that reaching a CP just below the cap (1493-1500) is generally a signifier of efficiently-used stats.
One final analogy that may help you understand this. In raids, a high attack is highly valued the whole concept of raids is that you’re battling against a clock. High attack accounts for higher damage per second, and a “better” raid pokemon is someone who can kill the raid boss faster. In pvp, the only “clock” is your pokemon’s health bar, and the damage that you put out depends solely on how long your pokemon can survive. Statistically, extending the “clock” by making your Pokemon bulkier yields better results than trying to maximize your damage at the cost of lower survivability.
As for your pokemon, Azumarill is so overpowered that you don’t really need a perfect pvp IV on it. I would suggest using the lucky Marill, as it will cost a lot less stardust (you will be powering it up past level 35), but if you have an abundance of stardust and a candy shortage use the Azumarill that you already have. As for Shieldons, the 10/13/15 will max out well below the 1500 mark, so the 15/14/15 will be slightly better here, simply because of how low Bastiodon’s CP growth is, although the difference will be minimal and both are great (a unique case – gostadium.club data). Both of these have very small CP per level growth and max out just over 1500, which allows for some leeway when choosing the perfect IV’s. As for the Toxicroaks, the 10/15/15 is actually a very good pvp IV, and I would suggest powering that one up as it has substantially better stats than the one you’re using right now. As you can see, it has a few fast-moves worth of extra bulk, and the difference in attack is very little because what it loses in IV’s it makes up for in a gained level.
IV: Atk Def HP
14/12/15: 1471 137.74 88.76 128
10/15/15: 1494 136.89 91.67 130
I hope this helped! If you have any specific questions, feel free to reply to the thread. Good luck.